Automatic control for heat transfer systems



S. P. MILLER July 11, 1944.

AUTOMATIC CONTROL FOR HEAT TRANSFER sYsTEMs Filed sepia. 4, 1941 4Sheets-Sheet l A S2/vlag l?? ...LNL QNNU NN AI wmN .uh hx i .mwN f RNsa) T KQ LMNEUNNU NN. N O

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July 11, 1944. a P, WLLER 2,353,486

AUTOMATIC CONTROL FOR HEAT TRANSFER lSYSTEMS Filed sept. 4, 1941 4sheets-sheet 2 E e@ 1 e "E155 Us) Hd* va i Si e 'l N e www 1211; v l 1|S. P. MILLER July 11, 1944.

AUTOMATIC CONTROL FOR HEAT TRANSFER SYSTEMS 4 Sheets-Sheet 5 Filed sept.4, 1941 4 Sheets-Sheet 4 s. P. MILLER Filed sept. 4. 1941 AUTOMATIC`CONTROLv FOR HEAT TRANSFER SYSTEMS July 11, 41944.

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Patented July 11, 1944l AUTOMATIC CONTROL FOR HEAT TRANSFER SYSTEMSsamuel P. Miner, chicago, n1.

application september 4, 1941, serial No. 409,460

12 Claims.

My inventionrelates to heat transfer systems, and more particularly, toself-regulated heat transfer systems or automatic control means forsteam heating and drying systems or for other desired uses or purposes.While the invention will be shown and described in connection with asystem for drying paper of various grades and content, textiles and thelike, it is to be understood that my steam heating and condensationsystem is adapted for use in connection with any desired heating ordrying unit or units the sections of which may be arranged forsimultaneous or independent control and regulation in any desiredarrangement.

Another object of the invention is to provide a heat transfer systemautomatically controlled or regulated within itself without humanintervention and in which the pressure or. degree of vacuum throughoutthe entire system may be maintained at a substantially uniform andpredetermined point constantly and at al1 times or at differentpressures at different points in the various sections or units accordingto the purposes of the system and the work to be performed and in whichthe pressure and temrature may be maintained accurately at any desiredhigh or low point or at any intermediate point therebetween, eitheruniform and predetermined throughout the entire system or at differentpressures and temperatures at different points or in the varioustransfer units or sections of the system.

Another object of the invention is to provide a heat transfer system orautomatic control or regulating means for steam heating and dryingsystems having one or more transfer units, which may be produced at aVery small cost and one which may 'be employed with known heat transfersystems without occasioning expensive changes and in which the pressurein the auxiliary or secondary steam line, in the units or at otherlocations may be maintained at a very low point, even below atmosphericpressure, as well as at any other desired pressure above atmospheric,and yet vprovides sufficient heat for the, transfer system or accordingto the use to which the system is put.

Another object of the invention is to provide a novel, simple andaccurate heat transfer sysupon the conditions and results to beobtained, and automatically or self-regulated, that is, without human ormanual intervention. l

In heat transfer systems as heretofore employed, proper regulation ofthe temperature has been very diflicult,4 if not impossible, andrequired constant attention and manual manipulation in order to maintainthe temperature on the various units constant or at the desired ornecessary pressureand temperature, especially where the demand on thesystem or units at various points varies from various conditions.

It is therefore an important object of the present invention to providea simple and novel au-` tomatic orself-regulation or control of heattransfer systems used for heating and drying or otherwise, which can beconstructed into the system initially or applied to known systems atcomparatively low expense and which will eifectually, when set oradjusted, accurately and dependably regulate and control the entiresystem or the various transfer units thereof at different temperaturesand pressures at various points so that when once set, it will stay setand continue to operate at the desired pressure/Sand temperature andinsure complete and free circulation, as well as the ordinary vacuumpump. In other words, in

accordance with the present invention and system, or self-regulating andautomatic control means, continuous, free and unimpeded circulation andaccurate regulation is assured,

tem and self-regulating or automatic control The present inventionrelates further to an improvement upon said system where the controlincludes a return line connected to the opposite side of the control orreducing valve and diaphragm chamber so that the regulation or effectdue to slight changes in pressure and temperature upon being set for acertain differential, is not only more sensitive, but more accurate andquicker whether controlling a plurality of units or each individual unitindependently or separately. Thus, in high pressure heat transfersystems such as employed in heating or in drying machines, the exhauststeam from one unit may be carried to the next unit after the condensateis removed therefrom, by employment of a flashV tank in which' thecondensate and vapor lare heated to generate and maintain the steampressure in succeeding units by employing the latent heat in the steamfor evaporating the water in the web or in heatingn the varioussucceeding transfer units.

In some heating or heat transfer systems, the steam is supplied to oneunit and then, after doing its work by heat transfer such as in heatingor drying apparatus, the steam is supplied t the next unit or sectionand so on through successive units until the last one is heated, whilein other systems, each unit receives its supply of heat directly fromthe main or live steam supply or a secondary fed thereby and the presentautomatic or self-regulated control means ls applicable to either systemand operates not by means of a separate water pressure pipe or by directconnection to the main or secondary steam supply, manifold pipes orheaders alone, but from the far or low pressure side of the systemeither at the units or a drain or outlet thereof under low. suction orvacuum pressure which may be i or l2 inches of vacuum in a vacuum orlow,pressure system and correspondingly higher in a high pressuresystem. The gas equalizingor control lines for automatic regulation ofthe heating of the units forms a loop or continuous circuit which isconnected at its ends to opposite chambers of the control valvediaphragm or piston instead of to only one side and thereby 'becomesmore sensitive and extremely accurate in maintaining 'the steam pressureat a predetermined point for each or all units and con-smtaccording tothe adjustment or differential.; for which it is set, thus insuringuniform heating and results. In the type of heat transfer systems knownas vacuum or low pressure systems, exhaust steam from a power generatingengine is employed to supply heating systems or other heat transfersystems. In such systems, the primary steam line from the boiler orother source of steam is provided with a bypass, one side of whichsupplies steam to a power generating engine under boiler pressure andthe other side supplies steam under the same pressure to a reducing orregulating valve which, in turn, communicates with and supplies steam tothe main secondary steam line. The exhaust steam from the powergenerating engine is received in a tank also communicating with the mainsecondary steam line and a vacuum is preferably maintained therein andexhaust steam receiving tank in order to increase the efficiency of thepower generating engine and the heat transfer system. Under suchsystems, steam may be `delivered from the boiler to the heat transfersystem at as much as 10 inches of vacuum, if desired, and this vacuummay be maintained at a constant degree by the automatic opening andclosing of the regulating or reducing valve interposed between theprimary from the boiler and the main secondary steam line. While such aresult is highly desirable and increases theefdciency of the powergenerating engine and heating system, it is not adaptable to highpressure heating or heat transfer systems such as used for heating anddrying purposes and particularly where the steamused or condensed in thesystem is at a very high percentage and the present invention rendersthe system adaptable for both uses. In other words, the presentinvention is equally applicable to low pressure or vacuum systems aswell as to high pressure heating, drying or heat transfer systems, asbefore pointed out, and

results in a more sensitive control or automatic Y regulation andmaintenance of a uniform pressure and temperature in each of a. seriesor plurality of transfer units of a system where simultaneously orindependently controlled units are employed 'by positioning andconnecting a reducing and control valve for a plurality of unitsorbetween each pair or one unit and its succeeding unit, which isespecially adapted for drying soft or tissue papers, or in othercombinations thereof such as between a. plurality of units atv thecalender, dry or discharge end and a single unit or one or more units atthe wet, entering or feed end. 'I'his is due to the low pressureregulating or control lines being connected to the steam supply controlor regulating and reducing valve for supplying additional or live steamto the system, on opposite sides of the diaphragm or piston thereof,connected to actuate the valve at the opposite pressure chambers thereofinstead of to one side only thereof, thus also allowing a suction orvacuum pump to be employed to quickly exhaust or withdraw water, air andinsoluble or non-condensable gases from the entire system and renderingthe same and the valve quickly responsive to slight pressure andtemperature changes to supply live or fresh steam to the system at thehigh pressure and temperature side to maintain the heating uniformthroughout or at the various independent or individual units, series ofunits or drying rolls or cylinders, or each cylinder, constant accordingto the pressure and temperature for which they are set, either high, orlow or vacuum pressure, and keeping the differential between adjacent orsucceeding heating units or cylinders constant at all times without anymanual effort or intervention. This reducing valve may be set to taperthe pressure and temperature in the entire set of rolls or cylinders,say from 30 to l0 pounds or even to a minus or 10 inches vacuumpressure, or any other dierential wanted, and the gas control orequalizing lines will quickly equalize each individual roll and keep therolls from air or gas binding, as well as stop the individual rolls fromcreating a vacuum or going to a lower pressure due to rapid condensationof the steam while, at the same time, only employing very small pipes ofone-half and onequarter inch diameter or substantially so, which can bequickly and economically installed and connected to known systems. Thereturn from the rolls may be trapped or not as the case may be, and asteady or fixed differential allows a steady flow of steam to each rollwith exact temperatures provided for and causing a more even and uniformdrying of the paper where employed for such purposes. The equalizingcontrol lines vent each roll separately allowing non-condensable gasesto flow up from each roll or cylinder and pass or be carried off and thecondensate flow down from each roll for drain or return to the steamgenerating system or |boiler. In this way, the heating or drying unitsare properly regulated whether connected to a steam supply line directlyor clirectly controlled or indirectly thereof or indirectly controlledto diierent regulators and whether the steam is caused to successivelypass through said units to maintain the steam at different temperaturesor pressures in the different units or series of units as where the usedsteam from one unit passes to the next leaving a region of higherpressure and enters one of lower pressure so that whatever condensateremains is partly or largely converted into steam at the desiredtemperature or passes directly to the diderent units independently `ofeach other from the main or secondary steam supplies as live steam yforheat transfer, absorption, condensation and discharge.-

Another object of the invention is to provide a novel arrangement andconstruction vof` Siphon ofa siphonsystem for discharging and drainingthe waste water of condensation and condensed steam from within thedrying cylinders as used in drying machines through the trunnlons onwhich the cylinders revolve or are driven, said condensate beingcondensed from the steam used in heating the transfer units orcylinders.

Other objects and advantages will appear and be brought out more fullyin` the following specification, reference `being had to theaccompanying drawings, in which:

Figs. 1 and 1A are a diagrammatic side elevation of a portion of a papermaking machine. showing the drying rollers or cylinders equipped with myautomatic control system;

Fig. 2 is an enlarged vertical sectional view of a control or regulatingand reducing valve employed in connection with my control system;

Fig. 3 is an enlarged fragmentary end elevation of one roller, Withthesteam supply, drain and regulating connections thereto;

Fig. 4 is a section taken on the plane of the line 4 4 of Fig. 3, andshowing also the lower portion of the roller'or cylinder; Fig. 4A is asection taken on line 4A--4A of Fig. 4; and p Figs. 5 and 5A is adiagrammatic side elevation corresponding to Figs. 1 and 1A, of a modiedform of the control system.

v Referring to the drawings, in which I have i1- lustrated two diierentembodiments of the invention, and particularly to the form shown inFigs. l to 4A, inclusive, I0 indicates a steam generator or supply shownas a conventional type of boiler which is employed to deliver steam atany suitable pressure to a primary steam supply pipe or line II, and I2designates a boiler shutoif valve adjacent thereto. I3 is anautomatically controlled regulating or reducing valve, the high pressureside of which is connected to the primary steam line II and controls thedischarge of steam at its low pressure side into a main secondary steamdistribution pipe or line I4 forming a manifold or header of a pluralityof units or sections designated as Section 1, Section 2, Section 3 andSection 4, the first being at the calender or hot dry end and the lastat the Wet or entering end, also designated as the receiving end for thewet pulp web from the paper making machine such as an ordinaryFourdrinier machine and the dry end being the discharge end for thefinished product, the paper P passing around the various rolls orcylinders of the drying machine, part or apparatus and any desirednumber of rollers or cylinders being employed in each unit or section,as desired, or as is customary and common in the art. For convenience,three of such cylinders are shown in Sections 1, 2 and 3 and 8 cylindersare shown in Section 4 by way of illustration, but the number usuallyemployed generally varies from 5 to 8, or otherwise, as desired. Theillustration of three cylinders in the rst three sections or units ismerely for the purpose of illustration and to condense the drawings orshowing instead of extending the same as in Section 4. Extending fromthe main secondary supply line or header I4 are a plurality of branchsteam supply lines or pipes I5, which branch or.

auxiliary lines may be of any suitable size, but are shown smaller.'I'he branch pipes I5 lead into the trunnions of the various rollers orcylinders I6 of the different sections or units of which Section 1 isillustrative. This steam is supplied around outlets or drains I'I forused steam or water of condensation from which the water is dischargedor drained into a return main or header pipe I8 located below, althoughI wish to have it understood that I do not desire to be restricted tothe employment of this specific arrangement'with the supply lines at thetop instead of at the bottom. The return discharge or drain pipe I8extends into the top of a flash tank I9 into'which the previously usedsteam along with the vapor and condensate which is subjected to theaction of the steam to generate additional steam or cause the same toash or pass into the steam outlet 20 leading from the top of the tankand to the next unit or section. A drain 2I for water extends from thebottom of the ash tank I9 to carry oi waste Water or condensate. A gauge22 is provided on the secondary line I4 at any suitable point such as atthe far end to indicate the pressure of the steam therein and a gauge 23for similar purposes may be provided upon the flash tank I9. Continuingfrom Section or Unit 1 to Section 2, it will be noted that the latter isof substantially the same construction and arrangement, including a-manifold, header or secondary steam supply line 24 also extendinghorizontally and in this instance, from the top of the steam outlet 20instead of from the main supply II and the valve I3 as is the mainsecondary supply line I4. Otherwise, the construction of the subsequentSections 2 and 3 is the same as Section l and the line 24 may beprovided with a similar gauge while the flash tank I9a is provided witha gauge 23a. In this instance, the return lmain or header drain pipe isdesignated at I8a and the flash tank I9a has a steam outlet 20a and adrain pipe 2Ia, in addition to the gauge 23a.

Each of the cylinders has a trunnion or roller bearing 25 on which theends of the cylinders rotate and have support, the cylinders beingdriven to revolve at any suitable speed and in any desired way as iscommon in the art. The bearings are designated at 26 and are in the formof a stationary frame which may form the sides of the drying machine orindividual bearings therein ln which are pipe ttings 21 or suitablenipples connected or threaded as shown at 28 and having passages 29 forthe entrance of the steam. Suitable connections are made with theoutlets or drains II of a siphon system which may include a tube orbushing 30 carried by, and attached` to, or forming a part of thebearing 26 which are shown tubular and extending from the inner endthereof axially of the trunnion in alignment with an outer tube 3Iforming a part of the fitting 2'I and receiving the drain pipe I'Ithrough the medium of elbows I'Ia and nipples IIb as shown moreparticularly in Fig. 4 of the drawings. A Siphon pipe 32 is threaded at32a in the tube 30 separate from the nipple Ilb and this siphon pipe hasan inclined outer portion 32h and is then bent at an obtuse' angletoward its inner portion 32e which is inclined or slightly divergentfrom the cylindrical wall of the cylinder so as to incline at a slightangle with an enlarged inlet end 33 of convex curvature corresponding tothe curvature of and spaced from said cylindrical wall as seen in Fig.4A in the shape of a funnel or ared end permitting free outlet of thecondensate. All of the cylinders are so equipped to provide a siphonsystem ofV drains for the cylinders.

The steam outlet 20a leads into a branch manifold or auxiliary steamline 34 constituting the manifold or header of Section 3, the same asthe steam outlet 20 leads into the auxiliary steam line 24 of Section 2to convey the exhaust and flash steam from Section 1. However, inSection 3, the drain pipes are denoted I1c corresponding to the drainpipes Il of Sections 1 and 2 in which automatic steam traps 35 areinterposed inthe form of trap valves which allow the water to bedischarged without apparent loss or passage of steam into 'the returndrain pipe or header Ib which empties into the flash tank IBb providedwith a similar steam outlet Zlib corresponding to the risers or outlets20 and 20a. The ash tank for condensate is provided with a drain 2lbwhich may lead toa discharge or return to the boiler. A similar gauge23h may be provided upon the flash tank I9b.

The automatic regulating or reducing valve I3 controlling the supply ofsteam to one or more units or sections and cylinders thereof or otherheat transfering elements or units is preferably constructed as shown inFig. 2 of the drawings in which the high'pressure side connected to theprimary steam line I I has an inlet or inner chamber 36 within thecasing of the valve I3 and has a pair of Valve seats 31 through whichthe steam passes and' an outer or outlet chamber 38 on the opposite sideof the internal wall provided with the seats 31 at the low pressure sideleading to the main secondary steam line o'r header I4. A packing glandis connected to the valve casing as by threading the same into the loweropen portion thereof through which access is obtained to the interiorstructure and this gland has a small bore 39 in which a stem 40reciprocates, the stem having an enlarged upper end portion 4I providedwith a pair of valves or valve heads 42 to cooperate with the s eats 31in the Valve structure body. In the gland or attaching portion whichreceives the stem 39 is a packing gland 43 sealing around the stem andclosing off the escape of steam within a frame or hanger 44 suspended lfrom the casing. The enlarged lower portion of the stem carries or isformed with an upright post 45 which is operatively connected to abalance lever 45 pivoted in the frame 44 at one side and havingadjustable weights 41 on the arms thereof adapted to be set for anydesired pressure operation according to the differential established ordesired to be maintained as well as the pressure of the steam and degreeof heat to be sustained in the transfer units or cylinders connected tothe valve. This post 45 operates through a diaphragm casing of apressure control means 48 which may be diaphragm or piston controlled.In the present instance, the post 45 is shown. connected to a diaphragm49 in the casing 4B, forming a lower pressure compartment or chamber I)and an upper pressure compartment or chamber 5I, the former of which isconnected to a control pipe 52 forming part of the control or pressureequalizing system and which, in this instance, is of small diameter,preferably about one-half inch, shown extending upwardly and along thesecondary supply pipe I4. The pipe 52 may be arranged at any suitablelevel instead of below the secondary I4 and may be in line therewith orabove the same, to which point it is extended as shown in Fig. 1. Thispipe 52 is connected to the relatively high pressure or supply side ornear end of the secondary I4 of the section or unit I, but is conynected to the low pressure side'orfar end atvthe drain pipe 2lb by adown pipe 63 with an interposed automatic trap valve or thermostaticsteam trap 53. At the near end or high pressure side, the pipe 52 isconnected by a smaller pipe 54, preferably about one-quarter inch indiameter,

to the secondary line I4 at any suitable point along its length andpreferably disposed in an inclined position away from the pipe 52 to theline I4 to drain and subject the control line to the pressure thereinbut preferably adjacent the branch pipes I5. Branch control lines 55 aret preferably tapped into the pipe 52 along and above the secondary lineI4 in each of the respective units or sections and depend therefrom forconnection with the respective cylinders at their outlets I1 at thedischarge sides or ends of the rolls I6 by connection with the elbowsI1a as seen in Figs. 3 and 4. These upright downwardly extending pipesare also preferably of smaller diameter than the pipe 52 or aboutone-quarter inch in diameter and constitute leads therefrom to therespective heat transfer elements or units such as the cylinders orrollers I5. Loose or swing joints 56 are preferably provided in theconnections 55 inclined as shown more particularly in Figs. 1 and 3 tohave vertical movements to compensate and allow for expansion andcontraction of the connections and the relative movements between thevarious parts of the heating or drying system and pipes constituting thesame in connection with the cylinders. .The control lines or pipes 55may be provided with valves 58 so that each heat consuming unit, roll orcylinder I6 may be individually controlled or cut off for purposes ofreplacement or repair or any adjustment that may be needed; At the faror low pressure side or end of the equalizer 0r control -III line orpipe 52 a connection 59 is made to a return control or equalizer line orpipe 60 which is preferably of corresponding gauge or size, that is,one-half inch diameter and this pipe 60 extends or returns to thecontrol or operating means 48 of the reducing or feed valve I3 to form aclosed circuit or loop in the control line and is connected to the upperpreferably closed or sealed chamber or compartment 5I of the diaphragmcasing or pressure control means 48 for actuating the valve I3 as shownmore particularly in Figs. l and 2 of the drawings.

The ash or exhaust steam from the tank or condensation chamber Ib isdischarged through the outlet 20h, the steam having been successivelyreduced in pressure and heat in each succeeding section or unit so thatwhereas theremay be a 30 pound pressure in Section 1, this may be 20pounds in Section 2 and 10 pounds in Section 3 or any other differentialwanted, or, if the pressure is lower in Section 1, it may be reduced toa minus or vacuum pressure when it reaches Section 4 at the dischargeorA outlet pipe or riser 20h. or, at this point, the pressure may be 5pounds, more or less. This steam is discharged into a control orreducing valve I3a corresponding to the valve I3 and having a similardiaphragm or pressure control adjustable by the weights 41 to a minutedegree so that the operation will be as sensitive as desired ineffecting the supply of steam to the Section 4 or in cutting off thesame when the various heat transfer units or cylinders have beenequalized. It should be noted that inbe placed in multiple series withthe entire load or the near and far ends oi the secondary line may beplaced in series by means of the control or equalizlng by-pass lines 52,60 and: 68 to allow an equalizing o! pressure between the near and farends of t he secondary line to be registered on the control or by-passline in addition to having separate pressures and a predetermineddifferential between each of the units controlled by a common equalizingor by-pass line and structure as well as independently controlling a,single or each individual unit or section so that the diaphragm in thevreducing valve of the primary line being in communication with thecontrol or bypass line, the pressure on thediaphragm will vary accordingto the rate of condensation in the heat transfer units or cylinders andthe condensing units. Thus, exhaust steam may be used below or aboveatmospheric pressure for heating systems or at sub-atmospheric pressurein such systems or other heat transfer units where the condensation islow or very rapid. In low or vacuum pressure systems, there will be anemcient and economical heat and reducing oi' back pressure on the enginegenerating the exhaust steam and at the suction or vacuum pump and theinitial steam` may be reduced from 35 pounds to 19 pounds or less perhour per horsepower at definite inches of vacuum and the arrangemententirely eliminates all of the disadvantages of the necessity of usingwater for condensation in cases Where exhaust steam is used for heatingor process work at above atmospheric pressure.

In section or unit 4, the cylinders I6 are the same as previouslydescribed, and, in this instance, I have illustrated 8 of such cylindersaround which the paper P passes instead of three or more cylinders, asdescribed in connection with the previous sections, but it is to beunderstood that any number may be employed as found practicable. Inconnection with the secondary pipes or headers I4, 24 and 34, the risers2li and 20a may be connected to the horizontal headers by elbows 6I, thesame as in connection with the pipe or riser 20h and its horizontalconnection with the valve I3a and the ends of the headers or manifolds I4, 24 and 34 may be closed by end caps or plugs B2 after the last heattransfer unit or cylinder. Whereas the high pressure side of the valveI3a is connected to the pipe Zlib forining an outlet from the flash tankor condensation chamber I9b, the low pressure side or outlet isconnected to another secondary header or manifold pipe 64, which, inaddition to being independently controlled, is, like the secondarymanifolds I4, 24 and 34, auxiliary or subsidiary to the primary or mainsteam line II and the manifold 64 is provided with an end cap or plug 65together with the corresponding branch steam supply pipes I leading tothe cylinders I6 and the other connections and structure, the same aspreviously described in connection with Figs. 1, 3, 4 and 4A, but, inthis instance, the outlets or drains'are indicated at I 'Id leading intothe common bottom return pipe, drain or outlet manifold |80 anddischarging through an elbow 66, which may be similar to the elbowsI'Ia, into a discharge pipe B'I connected to a vacuum or suction pump 68which may be either the rotary or reciprocating type, from which a pipe69 leads to return to the boiler or steam supplyv or to a generatingengine or eX- haust', or to a drain `or hot well. A gauge 22a may beprovided upon the manifold pipe 64 correspending to the gauge 22 andthermostatic traps 35a may be interposed in the drain pipes I'Id thesame as the traps 35 in the drain pipes I'Ic for similarfunction oraction. The control or equalizing lines of reduced diameter, asheretofore specified, include a, pipe 52a corresponding to the pipe 52and connected to the lower pressure compartment or chamber of thediaphragm or piston casing 48 thereof controlling the valve I3a, andextending above the manifold 64 with a down or upright return pipe 83aconnected to the elbow 66 at the far end or low pressure side, as of thedrain IBc with an interposed thermostatic trap valve 53a correspondingYto the thermostatic valve or trap 53. A gauge Ill may be provided on anyof the depending branch control lines a corresponding to thetapped'control lines 55 but is shown on the last one at the far end ofthe section or unit 4 to obtain the pressure at this point. 'Ihe gaugesmay be used for inspection so that if any correction, readjustment,replacement or repair is needed, it may be quickly effected though,usually,l this will not be necessary. The return of the loop or circuitof the equalizer or control line is made through the pipe a which hasconnection at 59a to the pipe 52a at the far end of the latter and thepipe 60a is connected at its near end to the upper pressure compartmentor chamber 5I of the diaphragm or piston casing 48 of the valve I3a, thesame as the pipe 6I) previously described in connection with the valveI3.

In the operation of the system as described and with the valve I2 openthe desired degree, steam from the supply source is admitted into theprimary line I I to pass into the inlet chamber 36 of the valve I3.Previously, this valve is adjusted by moving the weights il along thelever Il@ at the ends of the arms thereof to establish a predeterminedpressure difference or differential between the first and last orsuccessive units of the dierent sections of the heat transfer or dryingsystem, which may be radiators or otherwise, and shown, in thisinstance,as cylinders having a high or low percentage of condensation orabsorption depending upon the particular application and use of thesystem. The valves 42 being unseated to permit the steam at the requiredpressure to enter the secondary line I4, pass through pipes I 5 into thecylinders I 6, while some of this steam is bypasse'd,that is, partthereof passes into the small control pipe 54 to the pipe E52 fromwhence it passes into the chamber 50,01 the` control device 48 andpushes upwardly on the diaphragm 49 together with the post 45 and stem40 tending to or to set the valves 42 against their seats 31. This steamalso passes into the various pipes 55, 6U and 63 of the control linesand thev upper pressure chamber 5I, and consequently the steam in thepipe 52 will follow the line of least resistance, and since it cannotpass the trap 53 into the drain 2lb from the flash tanks or condensationcollecting chambers, it will pass into the pipe 60, tending to establishan equilibrium or equalize the pressure therein and consequently willpass into the upperv chamber 5I therefrom but at such pressure as not toprevent seating of the valves 42, although normally the pressure in thelower chamber 50 on the lower face of the diaphragm 49 will tend toforce it upwardly and thus decrease the-opening of the valves 42controlling the admission oi steam from the primary Il to the secondaryi4 to reduce or cut ofi' the same when the pressure in the line E2exceeds a certain point to establish a differential or tends to equalizewith the pressure in the remaining control lines 60 and vice versa or,when in some cases, at a low, minus or vacuum pres,-s sure. The machinebeing operated, the percentage of condensation and absorption in thecylinders in heating and drying the paper is quite high, and thiscondensate with a variance or difierential of 2 pounds or 2 inches ofvacuum pressure between the branch inlets l5 and the outlets il willlift or Siphon the water of condensation from the cylinders l 6 so thatthe condensate will pass out through the siphoning pipes 32 and bedischarged through the outlet pipes il and4 drain manifold i8 to the ashtank or condensate chamber i9 as the cylinders revolve in contact withthe paper P under tension. The exhaust or used steam passing into thetank i9 will heat the water and vapor in the tank causing additionalsteam to be generated at a lower pressure than originally supplied andpassed therewith into the outlet or riser 2@ to the manifold or header2li constiuting the secondary oi the next unit or Section 2 and the sameoperation will be repeated in this section with drain through theoutlets il,

return llia and ash tank Ita while the water also drains through thepipes 2l and 2id to successive tanks for discharge at 2lbv to drain orto return to the boiler. However, the pressure in the second section orunit will be lowerso that it will operate at a lower temperature andthis will be successively reduced in Section 3 at a still lower pressureand temperature, but whereas the drain through the pipes il, is and Illawill be unimpeded so as to permit the used steam to exhaust therewithand pass into the manifolds 2t and 3&5, the latter through the outlet29a from the hash tank ita, the steam from the cylinders l@ oi' sectionor unit 3, each made up of a plurality of transfer units or cylinderssuch as indicated at i6, will be trapped or prevented from passingthrough the outlets llc by the thermostatic traps or trap valves 35since these traps will permit water to pass at a low temperature butwill not permit steam to pass, nor will it occasion any apparent loss inthe steam pressure and will close under certain temperature for whichset under the action ci the steam in the outlets llc, such steam wiiipass out through the outlet or riser 2% to the valve 93a to be suppliedto the maniiold @il ci Section 4 and corresponding elements and pipesthereof in the same manner as in connection with Sections l, 2, and 3,but at a lower pressure and temperature at the feed or wet end of themachine where the web of paper enters onto the rollers i5. As the paperor pulp web P is fed in at the wet end, which is at the lowesttemperature, it will be subjected successively to higher temperatures inthe succeeding sections progressively toward the calendar or dry endwhere the finished paper is discharged and in this form, any number ofsections may be simultaneously controlled but depend on the travel andexhaust of steam or vapor from one section to the other to establish adifferential between different sections `from 4the highest to the lowestof the sections jointly controlled by a single control means butdirectly controlled by the latter. When the temperature and pressure issuch in the pipes 52 or 52a and lower chambers 5@ or higher than in thepipes or Sila and upper chamber 6l according to the setting of theweights 4l ,of the levers i6 of the control device' titi, as to raise orpush the diaphragm 49 upwardly, the valves d2 will be Closed and thesulpply of steam cut off, this being normally caused by the directconnection of the line 52 with the secondary Id at the pipe E4 which, asbefore stated, is preferably inclined to drain all moisture therefromand avoid obstruction by water or gas. Whether operating at vacuum orhigher pressure and as applied to steam or heat transfer or consumingunits in the form of cylinders or otherwise, should the pressure in anysecondary ifi, 2li or 3d or in any of the cylinders I6 and lines 55 fallbelow a certain point at which the device is set to operate, this willimmediately lower the pressure in the pipe E2 to permit the diaphragm i9to move down as shown in Fig. 2 and open the valves (i2 to admit steamto the secondary lli and the entire system as previously described dueto the unbalancing of the lever L36 from its adjusted position afterbeing equalized and due to the steam following the line of leastresistance or entering the 'pipe having the smallest pressure thereinand continuing to do so until the pressures are equal. Since thepressures in the pipes y52 and 6G and chambers 50 and 5I aresufficiently great, the valves t2 will remain closed depending upon theadjustment of the weights tl, suicient to raise the piston or diaphragmd@ to close valves 32. This action will take place in any one of thesecondaries or in any cylinder so that each set or cylinder or each unitwill actuate the control mechanism to admit steam for simultaneous orindividual control so that the entire system will be readjusted oroperate to maintain. a certain predetermined adjustment or differentialfor which it is set. By having the control or by-pass lines connected toboth sides of the diaphragm which actuates the control or reducing valveby control lines 52 or 52a to the pipes 5d or Sila with the near end ofa secondary such as lli or 6d, and to the cylinders i6 at the pipes 55at the low pressure sides or exhaust outlets ll, I'lc and I'ld and tothe return control lines or pipes d@ or Gila, the regulation becomesmore sensitive, quicker and more accurate and is especially adapted forpaper inaking machines but will operate in connection with other heattransfer systems using cylinders, radiators, or otherwise. The reducingvalves I3 or i3d may be set to operate at any desired pressure or toclose or open on a balanced or an unbalanced vpressure at opposite sidesof the diaphragm, depending upon the adjustment thereof by the weights@l and in low pressure or vacuum systems may be set at 10 inches ofvacuum and the vacuum pump may be set to maintain a vacuum of 12 incheswhich gives a differential oi 2 inches for causing circulation ordischarge of condensate or water. This ,will allow a temperature ofsteam in the control or by-pass lines 52 and til to be maintained at thetemperature of steam at 10 inches of Vacuum, and when the thermostatictrap 53 or the traps 35 startte open atthis temperature or' pressure,this will allow l2 inches of vacuum in the return lines to pass to thecontrol or by-pass line and lower the pressure in the secondary line aswell as under and at both sides of the diaphragm depending on theadjustment of the weights l of the reducing valve structure i3, thuscausing the valves t2 to open to admit more steam to the system untilthe temperatures and pressures 1n the control lines have reached the settemperature and pressure at which the device and system is adjusted tooperate, when the system and thermostatic traps 35 and 53 or 35a and 53awill be closed, cutting off the vacuum pump from the control or by-Ipasslines 52 or 52a, 60 or 80a. The thermostatic traps will be balanced tomaintain the degrees of heat throughout the heating system at thetemperature of steam at which the reducing valve is set, but, thistemperature and pressure will be affected by the condensation andabsorption in each unit, section or set of cylinders, as well as in eachindividual cylinder constituting one form of steam or heat transfer orconsuming unit so that the entire transfer system will be affectedto'effectually maintain the desired temperature and pressure throughout,at and from any point inthe system. This will also affect the operationof Section 4 by controlling the exhaust or flash steam entering the pipe20h and the thermostatic valves 35 and 53 will maintain the temperaturesin Section 3 and the preceding Sections 1 and 2, while maintained atsuccessively higher temperatures and pressures, re'- ceive and dry thepaper web in a reverse order insofar as the volume of moisture thereinis concerned. Section 4, however, will be independently controlled atthe valve i311 in the same manner at any point in the system by a dropin pressure and temperature or by the opening of any ofthe s'feam traps35a or the trap 53a which is particularly affected by the action of theexhaust or suction pump 68 at the desired differential or pressure lowerthan in the control line whether at a minus pressure or vacuum, or ahigh or posi+ive pressure. Thus, the control or reducing valves I3 andi311 are normally closed to cut "1T the suprlv ofsteam and no openingthereof will occur until the equalization of pressure occurs in thecontrol lines or sufilcient pressure to overbalance the action of theweights so as to depress the diaphragm il@ and unseat the valves H2 toadmit additional steam until such time as the pressures adjustthemselves to raise the diaphragm or piston t9 to close the valves t2.

In the form of the invention shown in Figs. and 5A, instead of having amultiple of sets or units of heat transfer or steam consuming devices orcylinders, all controlled by a single valve and control line or means inseries or otherwise as in Figs. 1 and 1A, each of the units designatedas Sections A, B, C and D are independently controlled by separatevalves and control lines in-I stead of merely the last section withlowest, pressure and temperature such as Section 4 in Fig. 1A which isso controlled because it is desired to maintain the same at a lowtemperature at the wet or entering end of the paper web where it isundesirable to expose the same to a high temperature or degree of heat.While not limited to such use, the arrangement shown in Figs. 5 and 5Ais especially adapted for soft o: tissue papers, particularly because itlends itself to extremely sensitive control and where the heat and steampressure may be as high or as low as desired with large or smalldifferentials between the different sections. In this form. theconstruction and arrangement for each section is substantially the sameas previously described for a plurality of sections as in Fig. 1 or asingle section as in Fig. 1A, although, in this form, low pressure orexhaust steam may also be used, As illustrated, the primary steam line II is adapted to be connected to a source of steam supply from a boiler,engine or otherwise, not shown,

Ilia

main IIh running as far as Section D, which is the last section orfarend of the system at the lowest temperature and pressure, but thefirst or entering section for the web at the wet end of the machine.From the header I Ih extend branches Ila, I Ib, I Ic and I Id to thedifferent secondaries 64e through regulating supply or control -valvesI3e which are of the reducing type as previously described and similarlyconstructed and controlled. From the secondaries 64e branch pipes I6extend to the steam consuming units or cylinders I6 which are providedwith outlets or drains Ile corresponding to the outlets Il, I'Ic and I1dpreviously described. Each of these outlets is provided with anadjustable automatic steam trap or valve 35e adjacent the drain pipe Iesimilar to the drain pipes I8, I8a, Itb and I8c. These pipes in SectionsA, B and C lead into condensation collecting chambers or condensatetanks |96 which empty through outlets or discharge pipes 2Ie into acommon drain or manifold 1I and have down or upright return pipes 63elike pipes 63 and 63a, as in Sections 3 and 4 connected to the controllines `52 and through pipe connections 59 with the control lines 60',the latter extending to the top diaphragm chambers while the pipes 52extend to the bottom charnbers. A thermostatic trapvalve 53e is alsointerposed in each pipe line 83e adjacent the drain or discharge 2Ie andoperates in the same way 'as the trap valve 53a. Each of the condensatetanks Ille is provided with a temperature and y densate tank Ilia isomitted and the drain manifold I8e is connected by a pipe Bl'e directlyto the drain manifold il at l2 shown as a T connection although,generally speaking, I have not desired to be limited to any form of pipeconnection, and. for this purpose, have omitted the specic reference tomost of the pipe connections throughout the description except wherespecically described to bring out a particular function. In thisinstance, the discharge from the pipe 61e and the drain II at theconnection 'l2 leads in to a suction or vacuum pump 68e having adischarge 6de to drain, for return to the boiler or to a hot well. Thepump 68e is designed to create a suction or vacuum pressure in the drainline to discharge the condensate passing through the trap valves 35e and53e, the latter of which is connected by a special fitting or elbow likettings Illa between the pipes I8e and 67e in Section D and has a down orupright return pipe 63e forming part of the control means connected tothe pipe 52 and through the connection 59 with the pipe instead of beingpositioned at the discharge end of a condensate tank I9e as in theprevious Sections A, B and C. In this way, any required differential maybe established at the far end of the machine to lower the pressure inthe down and control lines to clear the machine of condensate. Also,each section and each individual cylinder is independently controlledand adapted to operate at any desired pressure above or belowatmospheric pressure with any desired diierential between adjoiningsections or-between the first and last orany of the other sections ofthe sysand communicates with a conunon header or tem. Thus, in thiscase, each section is independently controlled instead of beingsimultaneously controlled or placed in multiple series with a commonsupply for steam or with the entire load, but it will also be understoodthat the near and far ends of the secondary line or any other suitableunits or sections thereof may be' placed in series by means of thecontrol or by-pass pipe and from different sources, or the same sources,or independently or simultaneously receive its supply of live or exhauststeam or vapor but that. in each instance, the arrangement of thedischarge` and drain pipes is such as to draw all condensate which wouldtend to block complete and free circulation of the steam and gases andavoids pockets due to the presence of non-condensable gases,particularly where a suction or vacuum pump is provided at the dischargeend. In each cylinder, two pounds or inches differential in pressure isusually'suflicient to cause the siphoning and discharge of the water ofcondensation through the Siphon system or pipes thereof and in this way,an eective and uniform heating is maintained according to any desiredpredetermined differential or set temperature. Also, the control linesbeing arranged in a continuous loop or circuit, will be readily cleanedout and subject to sensitive control to operate the supply valvesleading into the different secondaries and heat or steam consuming unitswhich may take the form of any heat transfer unit such as dryingcylinders, radiators or otherwise. Banks of gases, steam or vapor isprevented by the gas equalizing orcontrol lines and the reducing valvesmay be set to taper the pressure and temperature in the entire set ofrolls or cylinders, in addition to controllingand equalizing eachindividual roll or cylinder and preventing the same from air or gasbinding or from creating a vacuum or going to 'a lower pressure thanthat for which it is set, due to the lrapid condensation of the steamtherein. Also, it will be understood that the return or drain from therolls may be trapped or not as desired, and a steady or xed differentialestablished to allow a steady flow of steam to each cylinder with exacttemperatures provided for and to cause a more even and uniform drying ofthe paper. The equalizing control 1ines also vent each roll or cylinderseparately allowing non-condlensable gases to flow up from each roll orcylinder and pass or `be carried ofi and the condensate flow down fromeach roll at outlets or drains I1, i'ic, I'ld and lle for draining orreturning the same to the steam generating system or boiler. The meanswhich I have provided are simple as each cylinder or heat transferelement is provided with a riser and return and the return lines areconnected with the pressure or diaphragm chamber on opposite sides ofthe piston or diaphragm therein by means of the control or by-pass pipeswhich may be connected to a vacuum pump through the intervention of anautomatic trap valve to -pass water or moisture but prevent Athe passageof steam or vapor at a certain temperature for which adjusted, aspreviously described. By providing a thermostatic trap valve in the lineof the vacuum pump of the control or by-pass lines, extremely accurateregulation is insured together with a uniform maintenance of pressureand temperature in the different sections or units, each thermostatictrap valve being set to open at a definite temperature so that thevacuum pump will operate to cause the control lines to exert increasedsuction on the diaphragm of the reducing valve to admit additional steamas desired. The device also accurately controls the amount of vacuum orpressure in the heating system to admit steam from a primary linethrough a reducing valve to one or more units individually orsimultaneously in series. It will also be seen that fresh, live orexhaust steam may be used in the system controlling certain units,sections or sets of the heat transfer or consuming units of the systemwhether cylinders, radiators or otherwise. In view of the description ofthe operation of the form of the invention shown in Figs. 1 and 1A, andthe fact that Section 4 is independently controlled even though fed withused or exhaust steam, as well as the fact that each of the units orSections A, B, C and D of Figs. 5 and 5A is independently controlledfrom the main steam supply and thaiI each regulating or reducing valveite is set at dierent temperatures and pressures and to open at suchadjustment to maintain a desired diierential between any and all of thesections, it is thought that the operation of this form of the inventionwill be Sil readily apparent to any one skilled in the art in view ofthe foregoing description of operation, and, for this reason, furtherdescription thereof is omitted. However, it may be mentioned thatinstallations of the foregoing systems have accomplished an average ormean saving of approximately 20% with complete automatic control andwithout manual eiiort or human intervention, especially due to the factthat slight unbalancing of the pressure or temperature away from anestablished differential for which the device is set will, through thecontrol pipes and the lack of expansion prevented by the system, resultin immediate opening of the supply valves with greatly improvedoperation and increase in eiliciency of the heating or product producedtherefrom.

While I have illustrated and described the preferred form ofconstruction for carrying my invention into effect, this is capable ofvariation and modiiication without departing from the spirit of theinvention. I, therefore, do not wish to be limited to the precisedetails of construction set forth, but desire to avail myself of suchvariations and modifications as come within the scope of the appendedclaims.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

l. In a heat transfer system having a primary steam supply line and asecondary steam line connected to the primary line with a near end and afar end and a `return therefor, heat transfer units having inletsconnected to the secondary line and return, a regulating valveinterposed between said primary and secondary lines and controlling theadmission of steam from the former to the latter, and pressure actuatedcontrol means for said regulating valve, said control means including apressure chamber shut off from the atmosphere, a member movable thereinconnected to the valve and exposed to the steam pressure on both sidesthereof, and separate control pipes connected to the chamber at oppositesides of the member, one pipe being connected to the near end of thesecondary, to the outlets of the units and return and the other pipebeing connected to the far end of the rst control pipe.

2. In a heat transfer system having heat transfer units, a primary steamsupply line and a secondary steam line receiving steam from the primaryline and connected to the units for distributing steam to the latter,with a near end .and a far end and a return, a regulating valveinterposed between said primary and secondary lines controlling theadmission of steam from the former to the latter, pressure actuatedcontrol means for said regulating valve, said control means including apressure chamber, a member movable therein and exposed to pressure onboth sides thereof, a separate control pipe connected to the chamber atopposite sides of the member, one pipe being connected to the near endof the secondary, discharge ends of the units and return and the otherpipe being connected to the rst pipe adjacent the far end thereof andmeans for creating a suction in said pipes.

3. In a heat transfer system having a heat transfer element, a primarysteam supply line and a secondary steam line connected to the primaryline, a regulating valve interposed4 between said primary and secondarylines, pressure actuated control means for said regulating valve. aconnection between said secondary line and the element'for supplyingsteam thereto, a return from said element, said pressure actuatedcontrol means for said regulating valve including a pressure chamber, amovable member therein operatively connected to the valve, a controlpipe connected to the chamber at one side of the member, to thesecondary and return of the element and another control pipe connectedto the chamber at the other side of the member and to the remote end ofthe rst pipe.

4. In a heat transfer system having a `heat transferv element, a primarysteam supply line and a secondary steam distributing line connected tothe primary line and element, a regulating valve interposed between saidprimary and secondary lines, pressure actuated control means for saidregulating valve, a connection between said secondary line and theelement for supplying steam thereto, a return for said element, saidpressure actuated control means for said regulating valve including apressure chamber, a movable member therein operatively connected to thevalve, a control pipe connected -to the chamber at one side of themember, to the secondary and return and another control pipe connectedto the chamber at the other side of the member and to the remote end ofthe first pipe, suction creating means connected to the return and theto the first pipe and to the return pipe connection. 6. In a heattransfer system, a. plurality of heat transfer elements, a primary steamsupply remote end of the first pipe and a thermostatic 'trap valve inthe return.

5. In a heat transfer system having a primary steam supply line and asecondary steam line connected to the primary line, one or more heattransfer units, a regulating valve interposed between said primary andsecondary lines for supplying steam to the latter, a connection betweenthe secondary and each transfer unit, a discharge pipe connected to eachtransfer unit, a condensate return pipe connection to the dischargepipes, and pressure actuated control means for actuating said regulatingvalve and having control pipes, a pressure chamber, a diaphragm thereinconnected to the valve to actuate the same, said pipes being connectedat one end of each to the chamber on opposite sides of the diaphragm,one pipe being connected at its other end to the secondary between thevalve and the heat transfer units and at its opposite end to thedischarge pipes and return pipe connection, and the other pipe beingconnected at its other end line and a secondary steam line connected tothe primary line, a regulating valve controlling the supply of steamfrom the primary steam line to theY secondary steam line, supplyingconnections between the secondary and the elements, return dischargeconnections for said elements having a drain and pressure actuatedcontrol means for actuating said regulating valve including a pressurechamber, a diaphragm therein connected to the valve, a small controlpipe connected to the chamber on one side of `the diaphragm, to the nearend of the secondary in front of the elements and discharge connectionfor eachV element and another pipe connected to the chamber at the otherside of the diaphragm and to the rst pipe at the remote end thereof, andthe return pipe connected to the discharge connections and to the iirstcontrol pipe beyond the connection thereof with the secondary line andelements.

7. In a heat transfer system, a plurality of heat transfer elements, aprimary steam supply line therefor and a secondary steam line connectedto the primary line, a return pipe for said elements, a regulating valvecontrolling the supply of steam from the primary steam line to thesecondary steam line, supplying connections between the secondary andthe elements, return discharge connections from said elements having adrain and a pressure actuated control means for said regulating valveincluding a pressure chamber, a diaphragm therein connected to thevalve, a small control pipe connected to the chamber on one side of thediaphragm, to the near end of the secondary and discharge connectionsfor each element and another small control pipe connected to the chamberat the other side of the diaphragm and to the first control pipe at theremote end thereof and return pipe,

and a thermostatic trap valve interposed in the discharge return andbetween the latter and the first control pipe.

8. In a heat transfer system having a plurality of heat transfer units,a steam supply pipe for said units and a. return pipe therefor, acontrol valve in said supply pipe and controlling the admission of steamto the units, a pressure actuated device connected to said valve andincluding a closed chamber with a movable member therein, means forregulating said member and valve, a control pipe connected to thechamber at one side of the member and to the supply pipe between thevalve and the units, a discharge pipe connected to each unit and saidcontrolpipe, and another control pipe connected to the chamber at theother side of the member and connected to the rst control pipe near thedischarge end thereof.

9. In a heat transfer system of the class described having a pluralityof heat transfer units, a primary steam supply pipe therefor, asecondary pipe receiving steam from the supply pipe, a valve interposedbetween supply pipe and secondary pipe controlling the supply of steamfrom the former to the latter, a chamber closed olf from the atmosphere,a diaphragm therein connected to the valve and forming closed chamberson opposite sides thereof, a small control pipe leading frorn a closedchamber at one side of the diaphragm and having a connection to thesecondary pipe adjacent the near end thereof and'to the several units atthe discharge ends thereof, connections between the secondary and theunits for supplying steam to the latter, a drain pipe connected to thedischarge end of each unit, a return pipe connected to the drain pipeand to the far end of the ilrst control pipe, and another pipe connectedto the other closed chamber at the opposite side of the diaphragm and tothe first control pipe at the far interposed trap valves, a control pipeconnected to the pressure chamber on one side of the memlber, to thesupply pipe between the valve and the units, to each unit at itsdischarge end and to the return pipe, and another pipe connected to thepressure chamber at the other side of the member and to the return pipe,and suction creating means connected to the discharge and retiu'n pipes,said units being connected in series.

1l. In a heat transfer system, a plurality of heat transfer units, asteam supply pipe connected to the units for supplying steam thereto, acontrol valve in said supply pipe and having a pressure actuated meansfor admitting steam to the units and including a pressure chamber with amovable element operatively connected to the valve and means forregulating the same, a discharge pipe for each unit, a return pipeconnected to the discharge pipes with an interposed trap valve, acontrol pipe connected to the chamber on one side of the'element, to thesupply pipe between the valve and the-unit, to each unit at itsdischarge end and to the return pipe, and another pipe connected to thechamber at the -other side of the element and to the return pipe,

and suction creating means connected to the discharge and return pipes,said units being arranged in a plurality of series each connected withthe supply pipe through an independent control valve provided with asimilar control means.

l2. In a heat transfer system having a heat transfer unit, a primarysteam supply pipe, a secndary pipe connected to the supply pipe, acontrol valve between the supply pipe and the secondary pipe, a steamreturn pipe, said heat transfer unit comprising a cylinder having aninlet connected to the secondary pipe and a discharge pipe connectedaxially thereto, said discharge pipe having a syphon drain pipeextending down inta` the cylinder in divergent relation to theperipheral wall thereof and having an end portion spaced from said walland following the curvature thereof, a drain pipe connected to thedischarge pipe, pressure actuated control means for the valve adapted tobe adjusted to establish a predetermined dilerential between the supplyand secondary pipes and unit, a diaphragm cham- Y ber closed ofi fromthe atmosphere, a diaphragm

